I`d be tempted to suggest trying the probiotics as well.
We feed DD (she`s 2 1/2) a yogurt a day called Activia. It contains more active bacteria (the good ones needed in your intestinal flora ) than the usual yogurt's acidophilus and bifidus. You have to check labels on yogurts though. Some are so processed that bacterias are basically killed and you end up just with a dessert without much benefits ! Activia is supposed to be for kids 3 and older, but I`d say that`s probably in general.